1. Field of the Invention
The present invention relates to a miniature linear guide apparatus wherein a slider is supported by a guide rail through movable rolling members disposed so that the slider is movable in the longitudinal direction of the guide rail. More particularly, the present invention relates to an improved miniature linear guide apparatus which requires a small number of parts, and which is easy to assemble and very compact.
2. Description of the Prior Art
As prior art miniature linear guide apparatus, there are examples as shown in FIGS. 1 and 2.
In this prior art apparatus, a slider 52 is assembled to a guide rail 51 having a U-shaped cross section and is slidably movable in the longitudinal direction. The slider 52 is integrally formed by fitting a ball guide member 54 into a recess of a race member 53 having an inverted U-shaped cross section. Ball rolling grooves 1B are formed in the inner surfaces of the side walls of the guide rail 51 in the longitudinal direction. Similar ball rolling grooves 11B are formed in the outer surfaces of the side walls of the race member 53 so that the ball rolling grooves 1B, respectively, oppose the ball rolling grooves 11B. Balls 5 are disposed between each pair of ball rolling grooves 1B and 11B. The ball guide member 54, which has a pair of ball no-load circulating paths (hereinafter, referred to as ball circulating paths) 56 formed therein, comprises two members including an upper cover 54a and a lower cover 54b. The ball guide member 54 is integrally secured to the race member 53 by a rivet 57.
However, in the prior art miniature linear guide apparatus, since the ball guide member 54, located within the race member 53, is defined by two members of the upper cover 54a and lower cover 54b, and since these members are secured to the race member 53 by the rivet 57 integrally, the assembly is troublesome and assembly error tends to be caused. Furthermore, since each of the upper and lower covers 54a and 54b are molded by a separate metal-mold, a deviation is frequently caused between the upper and lower covers 54a and 54b due to a dimensional error of each metal-mold. When the deviation is caused between the upper and lower covers 54a and 54b due to the assembly error or dimension error, the rolling of the balls 5 in the ball circulating paths 56 is disturbed, and the ball guide member 54 is determined to be defective. As a result, a problem is involved in that the yield of product is degraded.
Moreover, since it is difficult to form the thicknesses of the upper and lower walls of the ball circulating path 56 extremely thin, another problem is involved in that when the upper cover 54a is placed on the lower cover 54b, the height of the ball guide member 54 becomes higher than necessary, and the overall structure of the apparatus becomes large.
In addition, since the number of parts of the apparatus is large, still another problem of high cost is involved.